Thesis
Risk-based crashworthy designs to enhance ship damage stability
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2022
- Thesis identifier
- T16445
- Person Identifier (Local)
- 201956704
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- SOLAS damage stability regulations have been continuously developed, strengthening a level of ship safety at sea. Nevertheless, many casualties from ship collisions and groundings are still occurring even these days. However, the current SOLAS regulations for passenger ships are not still enough to prevent the current risks. The fundamental problems are that design improvements with new materials and arrangements have been restricted, that individual ship sizes and operational profiles have been disregarded, and that solutions to design issues have been limited. Even though SOLAS opens a door for new designs through “New Technology Qualification (NQT)” procedures and the approval process of “Alternative Design and Arrangements (AD&A)”, they are too time-consuming as well as require expertise. Thus, they are not widely available in the market, stifling developments in this area. Hence, novel approaches and ideas are required to continue improving the stability of passenger ships in general. By addressing this problem conceptually, procedurally and methodologically, this thesis aims to suggest a new methodology with a quantitative risk assessment platform to facilitate and nurture developments in this direction. The method begins by selecting target subdivision zones with high risk via a vulnerability assessment, and several feasible risk control options (RCOs) are applied to these zones. Collision simulations of the region in question using crashworthiness analysis are carried out to determine damage severity in worst-case collision scenarios. The collision speed of a striking ship is derived from a series of pre-simulations, and the speed generating B/2 penetration is employed to fulfil the current SOLAS criteria. Given the penetration results, each RCOs’ cost, and the design change effects of each RCO on the target ship, a cost-benefit analysis is performed to find an optimum solution. The final RCO can be approved and reflected in ship design as an alternative solution by the relevant Administration according to the Approval Process of Alternative Design and Arrangements defined in the IMO. The proposed quantitative risk analysis is applied to a case study with a 65,000 GT medium size cruise ship. The relative collision speed of 10.14 knots from pre-simulations and a vulnerable Zone 15 are identified from the proposed methodology. A total of 26 passive-type RCOs are investigated, including single or double longitudinal subdivisions, different hull thicknesses and permanent foam void-filling measures. The nonlinear finite element method is employed to obtain the maximum penetrations of the stuck ship for all RCOs. Based on the cost and potential loss of life (PLL) of each RCO, the Gross Cost of Averting a Fatality (GCAF) is calculated, and the final three RCOs among all 26 RCOs are successfully identified as optimum solutions. It is also interesting to examine various simulation parameters' effects from a sensitivity study. The results prove that this methodology gives reliable outcomes regardless of different parameter values with a recommendation of 5% and 10% design margins for longitudinal subdivisions and hull thickness RCOs, respectively. The proposed methodology complements the current problems of SOLAS damage stability regulations, especially for p-factor, providing successful quantitative risk analysis for evaluating various crashworthy RCOs. Thus, this proposed methodology can be used as an alternative design solution for risk prevention or mitigation purposes, finally leading to customised safety designs for individual vessels based on their operating areas and profiles.
- Advisor / supervisor
- Vassalos, D. (Dracos)
- Boulougouris, Evangelos
- Resource Type
- DOI
Relations
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PDF of thesis T16445 | 2023-01-09 | Public | Download |